Edwin Hubble

Question 1

What observatory did he work at?

Answer 1

Mount Wilson Observatory

Question 2

The time

Answer 2

Albert Einstein had recently published his Theory of Relativity. Many ideas about the galaxy and the universe were changing quickly.

Question 3

The Andromeda Nebula

Answer 3

1923
It had stars like in our galaxy but dimmer
Not a forming solar system or star cluster in the Milky Way but a galaxy

Question 4

Cepheid Variable Star

Answer 4

Brighten and dim periodically.
Longer period=more luminous star.
Distance can be determined using the luminosity determined from the period and its measured brightness.

Question 5

Purpose of Cepheid Variable Star?

Answer 5

to find distance of Andromeda from Earth which is 2.48 million light years from us.

Question 6

Classification of Galaxies

Answer 6

Hubble discovered many more galaxies— enough to make comparisons between them
He divided them into 3 types: ellipticals, normal spirals, and barred spirals

Question 7

Redshift

Answer 7

Hubble studied the red shift of 46 galaxies.
By studying this redshift, he discovered that the galaxies are moving away from us, and the farther away a galaxy is, the faster it is moving away from us.

Question 8

His major discovery

Answer 8

The universe is expanding!!

Question 9

Milton Humason and Hubble come up with expansion rate

Answer 9

500km per second per megaparsec

Question 10

Hubble’s constant

Answer 10

Movement of galaxies is uniform expansion

Question 11

What was Hubble skeptical about?

Answer 11

The expansion of the universe.